Seventy-seven patients suffering from childhood onset absence epilepsy as well as their families were investigated for familial prevalences of epileptic seizures and migraine. Proceeding from the whole sample, epileptic seizures seemed to occur more often in the families of female propositi, though maternal relatives of females and paternal relatives of males were more often affected than the respective opposite groups. Migraine was more often diagnosed in female family members, which might be due to biased reports. Migraine prevalence was significantly higher in the mothers of female as compared to male propositi. The model of polygenic inheritance of epilepsy with sex-related thresholds of manifestation is discussed.